The Deadlift: Muscles Worked

By: Nick Soleyn, Editor in Chief and BLOC Staff Coach

With 206 bones, articulating at six types of freely moveable joints, and around 640 skeletal muscles in the human body, one could be forgiven for thinking that strength training is anything but simple. Anatomy, physiology, biomechanics, not to mention issues of economy and the efficient use of one’s time, there are a host of factors that influence the shape and structure of a barbell-based strength program. Yet, somehow, when we distill all those factors down, we end up with four core lifts: the squat, the press, the bench press, and the deadlift. Performed and used correctly, these lifts will make you stronger while leaving few holes in your muscular development. For the deadlift, the muscles worked are nearly tip to tail, making it one of the best lifts for building raw, functional strength.

The core lifts—or what we sometimes call the big barbell lifts—are basic human movements. Squatting, pressing, bench pressing, and deadlifting involve most of the body’s muscles, used in their primary functions. Your everyday activities involve some combination of bending, bracing, grasping, carrying, sitting, standing, and holding yourself erect against external forces—various joints acting together to produce coordinated movement. The barbell allows for progressive, incremental loading of these basic movements, making us stronger for the things we do every day.

We can produce widely applicable benefits with just a handful of movements because muscles only have one job. They contract, pulling at attachments to the skeletal system to arrange or move the body. So, we can train for innumerable expressions of strength using only a few lifts.

How Muscles Work

During voluntary single-joint movements, skeletal muscles have two basic functions. As agonists (sometimes called the prime movers), muscles attempt to accomplish some goal. If you want to perform a bicep curl, for example, your goal is to flex your elbow, bringing your hand closer to your shoulder. The biceps brachii and the brachialis are the agonists for that movement. Agonists muscles can act concentrically (shortening), eccentrically (lengthening), or isometrically (staying the same length). When you curl the weight in your hand toward your shoulder, the biceps brachii contracts and shortens. If you lower the weight slowly back toward the floor, the same muscles resist the weight, lengthening as they do so. If the weight is too heavy to move, then when you attempt to flex your elbow, the biceps muscles will contract but may remain the same length, in which case they are agonists acting isometrically.

The second basic function of a muscle in single-joint movements is to oppose the agonist muscle, creating stability. Antagonist muscles resist movement around a joint, working in tandem with agonists. In a throwing motion, for example, your triceps muscles are some of the prime movers, causing the quick extension of the elbow, but your biceps brachii and brachialis will now become antagonists, automatically acting to limit the triceps’ forceful extension and helping to prevent your elbow from overextending. The coordination of agonist and antagonist actions protects your joints during quick, explosive movements, allows you to maintain your balance and stay upright, and provides for fine motor control.

Beyond single-joint movements, muscle function becomes more complicated. For the big barbell lifts, the basic muscle functions are still appropriate: agonist joint extensors resist the weight during the lowering portion of the lifts, then contract concentrically on the way up. Their antagonist pairs stabilize and slow these concentric contractions. But these bigger movements also require other muscle functions and the organizing power of the central nervous system. Your muscles become joint stabilizers. They reposition joints to drive internal and external forces to different parts of the body. Built-in sensory receptors act as motion sensors, affecting your proprioception and your reactions to changes in the movement of the barbell and shifts in your balance. Most of these things happen without you thinking about it

Part of the criteria for selecting effective exercises for barbell training is that the lift trains large amounts of muscle mass. More joints and bigger movements mean that the big barbell lifts are not just training muscles. They train the whole body as a unit. Understanding how muscles work in each of the main lifts can highlight their usefulness for simple, hard, and effective barbell training as well as give us a starting point to examine issues related to learning, teaching, and programming the lifts.

What Muscles Does the Deadlift Work?

Deadlifts work more muscle mass than any other of the core barbell lifts.

Beginning with the bar on the floor at a dead stop, your feet placed under the barbell so that the bar is over the middle of your feet, taking a firm grip on the bar, and maintaining straight arms throughout the movement, the deadlift is little more than picking up a barbell. A technically correct deadlift requires that the lifter maintain rigid extension of the vertebral column and that the barbell moves in a straight vertical line from the floor to the lockout position. The starting and ending positions require that the lifter begins with flexed hips, knees, and shoulders and finishes with full extension of each of those joints. Every joint from your fingertips to your shoulder and from your shoulder to your feet are part of the kinetic chain of the lift, which means that every muscle crossing each joint between those points has a job. We can, therefore, consider the deadlift a full-body exercise, training the back, the “core” muscles of your trunk, the legs, the hips, and your grip.

Back and Core

Every joint in your body offers the opportunity for movement and the opportunity to absorb the force that is attempting to travel between two points, usually a base of support and some external resistance. Imagine trying to jump as high and as far as possible while completely relaxing all the muscles of your torso. What happens? You will end up neither very high nor very far from where you started, because the force generated by your legs and hips for the jump gets lost in your jelly-mold of a torso. Consider this in the context of daily life—getting up from bed, sitting in your chair, walking around. The ability to hold certain parts of your skeleton rigid, particularly your vertebral column, keeps you from existing as a bag of mush on the floor. In particular, as we are vertically oriented bipeds, we depend on our spines to keep us erect whether we are sitting in a chair, walking across the room, or lifting weights. Your spine keeps you erect, making it the most important structure for basic human movement.

The spinal column includes 33 interlocking structures, 24 of which articulate. That is a lot of opportunity for movement and a lot of opportunity for lost force traveling from your feet to the barbell in your hands. To move a deadlift, you push with your feet and open your hips. The ground anchors the movement by resisting the force generated at those joints. Imagine trying to deadlift while standing on a trampoline. You would sink before the bar breaks contact with the floor. Despite what our brains might be telling us during a heavy deadlift, we are not lifting the barbell with our hands or arms. We exert force against the floor first. That force travels from our feet against the ground, through our legs and hips, along our spines and to the barbell. Any structure between the floor and the bar that buckles will intercept some of the force that would otherwise contribute to moving the barbell.

The act of setting your back, squeezing your chest up and squeezing your lumbar spine into extension, allows the force generated by your legs and hips to reach the bar and move the weight safely and effectively. Much of the effort that goes into a heavy deadlift lies in the act of setting your back and maintaining that squeeze through the full range of movement.

The spinal erectors are three muscle groups that pull the spine into normal anatomical extension and contract isometrically when you “set your back” at the bottom of the deadlift—the Iliocostalis, longissimus, and the spinalis. At the top of the deadlift, they continue to hold the spine rigid, stacked to support the compressive force of the barbell and keep you upright.

As you start the lift, there is a fight between gravity acting on the bar to pull your arms straight and your latissimus dorsi muscles (lats) keeping the bar against your legs and pulling in a straight vertical path. The lats originate from the inferior aspect of the scapula (the shoulder blade), along the spine from T7 to L5, and down to the iliac crest of the pelvis. That massive muscle inserts on the anterior aspect of the humerus, pulling the upper arm to extend the shoulder and keep the bar back against your legs.

Aesthetically, the lat muscles are often thought of as back muscles; they are the big broad muscles that give your upper body a “V” shape. Functionally, the lats are back and shoulder muscles, assisting in maintaining spinal extension and extending, adducting, and internally rotating the shoulder. Due to the lats’ function, the deadlift is a key lift for anyone looking to improve both the strength of their back and their physique.

Training Your Trunk

The spinal erectors pull the vertebral column into the force-transferring position, but your trunk has muscles all around it to help keep the spine stable under load. The rectus abdominis (your abs), the transverse abdominis, and the interior and exterior obliques—the “core”—are all hard at work during the deadlift. In most normal movements, the muscles of the trunk work isometrically. The spinal erectors establish your posture, and the muscles of your abdominal wall squeeze and support it.

For a more functional core, one should load these muscles’ primary functions. The concept of progressive overload applies to the trunk muscles, just as it does to every other trainable skeletal muscle in the body. The muscles get stronger by being required to produce progressively more force. The deadlift is particularly effective in this due to the bent over starting position.

Legs and Hips

The primary movers of the deadlift are the muscles that extend your knees and hips. These powerful muscle groups contract concentrically, shortening, producing enough force to drag the barbell up your legs into a standing position.

The knee extensors are the muscles of the quadriceps group. “Quad-” indicates four muscles: the vastus medialis, vastus lateralis, vastus intermedius, and the rectus femoris.

One key to understanding muscle function is to look at each joint that the muscle crosses. One of the functions of that muscle will be to aid or cause movement around that joint. The rectus femoris starts on the hip at the anterior inferior iliac spine, running down toward your knee. It and the three vastus muscles—all of which begin on the femur—cross the knee and have primary functions as knee extensors. The big rectus femoris is the muscle that gives your thigh its “V” shape when you’ve been doing your squats and deadlifts with dedication.

At the same time as your knees extend, your hips open, extending until you are in a standing position. Hip extension is primarily the domain of the gluteus maximus, which recruits your hamstring muscles (the biceps femoris, semitendinosus, and the semimembranosus), and the adductor magnus of the inner thigh. The gluteus maximus is the largest muscle in the human body, which should clue us in that hip extension is an important and powerful movement. Nearly all big, powerful movements require some extension or rotation of the hip muscles, and the deadlift trains those muscles to maximum effect.

Arms and Shoulders

In addition to the shoulder functions of your latissimus dorsi “lats”, your trapezius “traps” muscles (“traps”) are critical to the strength and stability of your shoulder girdle. The lats and traps are the biggest muscles of the back, but function to stabilize the shoulder in the deadlift. Think of the top of the deadlift as one in which you must demonstrate impeccable posture against a heavy load. Your traps are postural muscles, and they resist scapular depression (the opposite of shrugging) to keep your arms in place, at home in the ball and socket joint of the shoulder. The deadlift trains your traps for exactly these functions, automatically and without you needing to do anything other than to keep your chest up and stand tall at the top of the movement.

Grip

It may seem obvious, but people often forget that the deadlift is a grip exercise as well. There are only a few muscles in your hand and forearm that contribute to grip strength. The flexor digitorum superficialis and flexor digitorum profundus flex, or “curl,” your fingers at the proximal/medial and distal phalanges, respectively (“digitorum” refers to your digits or fingers). The muscles that flex your thumb are the flexor pollicis brevis and the flexor pollicius longus (“pollicis” refers to the thumb). These muscles are extrinsic to the hand, meaning their muscle bellies are located on your forearm. There are some muscles intrinsic to your hand that contribute to grip strength, but they are smaller and dedicated more to fine motor functions rather than blunt grip force. Hanging onto the bar while you deadlift tests these muscles’ gripping capacity, and the heavier you lift, the stronger they must become.

The Deadlift is a Strength Exercise

Ultimately, the deadlift is a full-body, raw-strength building lift. It is a less technically demanding lift than the squat and, perhaps, the most primal of the core barbell exercises. There are few things as satisfying as loading up a bar with 1x, 2x, or 3x your body weight, gripping the weight in your hands, feeling the strain of every muscle in your body, then giving gravity the middle finger, and standing up.